


Demon Setter and King Cyborg

by Valgus



Category: Haikyuu!!, ワンパンマン | One-Punch Man
Genre: Abandoned Work - Unfinished and Discontinued, Alternate Universe - Character Swap, Comedy, Crossover, Drama
Language: English
Status: In-Progress
Published: 2015-12-13
Updated: 2015-12-14
Packaged: 2018-05-06 11:01:48
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 3,490
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/5414387
Author URL: https://archiveofourown.org/users/Valgus/pseuds/Valgus
Summary: <blockquote class="userstuff">
              <p>Hinata fought with Kageyama over volleyball like always, but when he went to apologise to his partner-in-volleyball, he found a blond cyborg with Kageyama's voice in the clubroom instead.</p><p>On other universe, Saitama went home not to his disciple, but to dark-haired high school student who didn't seem to have any superpower at all except being an amazing setter in volleyball game.</p><p>Will Genos be alright with his superpower cyborg body on a universe with no monster, only teenagers dedicating their life for volleyball? Will Kageyama be okay in a planet with monsters and crazy-strong superheroes?</p><p>And, lastly, will they ever return to their original universe?</p>
            </blockquote>





	1. Chapter 1

**Notes for the Chapter:**

> This happened kind of because both Kageyama and Genos' voice actor is Kaito Ishikawa...
> 
> I'm sorry. (Kinda.)

“Hinata! You dumbass! Why haven’t your receive got any better since last week?”

“It can’t be helped! We had mid-term exam! I pour some of my energy for studying!”

“That is a very unprofessional reason for a volleyball player! Who said he’s going to take the world with me? Is it not you?”

“Stupid Kageyama! I still have to graduate high school, you know! Stupid! Stupid! Stupid!”

That evening, when there was no practice since the hall was used, Hinata and Kageyama decided to train Hinata’s receive. Sure, it ended up with Hinata stomping away, face red and cheeks puffed, but at least they tried.

Kageyama picked up the ball they just used and sighed. If only he could take a break from _this_ life for a while…

But there was no time. Soon they would face harder battles with stronger enemies. Kageyama just couldn't stop training and getting even better at volleyball. Too bad Hinata didn't seem to think the same thing! That orange-haired dumbass!

Scowling at the volleyball, Kageyama held it on his hips and walked away.

*)*

“Sensei, what is your plan for today?”

“I’m going to buy some manga.”

Genos stared at Saitama’s face, no trace of expression he could deduce from his teacher’s face.

“What manga?” Genos replied, his hand over the book where he record everything about Saitama.

“Sport manga,” Saitama showed a smile before hoisting himself up. “Do you want to come?”

_I want to fight bad guys—or at least fight you. But what you did this whole week was waiting for that goddamn sport manga about some guys hitting ball over the net._

Genos looked up at Saitama, now already stepping on his sandals.

“No, thank you. I guess I’ll clean the bathroom.”

Genos closed his notebook and went to find bathroom cleaner. His steps felt heavy and he wondered what was so great about manga that his teacher, possibly the best hero ever existed, wanted to read it so much.

*)*

After eating chocolate-filled bread and talking to Yachi who stayed for student council business, Hinata started to feel worry about Kageyama he left alone at the yard. He went back to apologise, but Kageyama wasn’t there.

Hinata walked to the clubroom where they stored their bag, crossing his fingers in hope that Kageyama hasn’t come home yet. Peeking through the window, Hinata could see that Kageyama’s bag was still there.

So Kageyama hadn’t left just yet.

“Kageyama!” Hinata burst to the door and immediately bowed down. “I’m sorry! I was tired from all the studying and I sort of vent it out to you!”

“’Kageyama’?” Kageyama voice replied.

Hinata raised his head to check Kageyama’s expression, but instead of seeing his partner-in-volleyball Kageyama Tobio, Hinata saw a cyborg.

Or at least he thought it _was_ a cyborg. It has blond hair, arms that were definitely not human’s, and on the part where human’s eye supposed to have white part, its—or _his_ , judging by broad shoulders and lack of lumps on the chest area—was black.

“I was teleported to this place,” the cyborg talked, with the casually snobby Kageyama’s voice. “Do you happen to know in which city I am currently teleported to?”

Hinata stared at pulsing, blinking orange light under the cyborg’s arms and he gulped, slow and difficult.

“You’re not Kageyama,” he muttered.

The cyborg stood, “Affirmative. I am Genos from Z-City.”

Hinata didn’t know where Z-City was, but he knew he had to find Kageyama soon, wherever he was.

*)*

“Genos! I’m home!” Saitama announced as he stepped off his sandals. Whistling as he walked back to the living room, the bald hero couldn’t believe he was so lucky on getting the manga on discount.

“Genos?” Saitama called again.

The apartment was eerily quiet. Was Genos sleeping? Nah, he didn’t do things like that. Even if he did, he’d wake up upon Saitama coming home, as always. His so-called disciple could detect movement miles away, anyway.

“Genos…?”

There was a clicking sound from door handle being opened from the bathroom and Saitama breathed in relief. “So you were in the bathroom! Did you clean it up? Or did you actually dumping something? Ah, but you’re a cyborg—but wait, you can eat! Does this mean you still have to go to— _who are you?_ ”

Saitama furrowed his eyebrows and glared to a boy with dark, short-cropped hair who looked at him with wide, confused dark blue eyes.

“Kageyama Tobio,” he replied in Genos’ voice. “And who are you? Where am I? I thought I was going back to the clubroom to take my bag.”

“Clubroom?” repeated Saitama.

“Yes, I’m part of volleyball club,” ‘Kageyama Tobio’ replied. “To be exact, Karasuno High School’s Volleyball Club.”

Saitama raised his eyebrows. “Um—“ but then Genos’ phone, who was apparently left on the living room’s table, started to rang.

Saitama picked it up, considering the caller ID said ‘Hero HQ’.

“Genos! We have a cat-like monster approaching to Z-City. We’d like you to stop it before it goes over the city border!”

Saitama killed the line and put the phone back to the table.

“Kageyama Tobio, I must go,” he said, stripping and changing to his hero suit in a blink of an eye. “You better stay—ah, it’s actually safer for you to follow me, so I can keep an eye on you. Who knows, this cat-monster might be huge and it can destroy this place too.”

Kageyama Tobio made a half-confused, half-shocked expression.

“Cat monster?” he repeated in Genos’ voice, saying the phrase like kindergarten trying to say 'sub-atomic particle'.

**Notes for the Chapter:**

> LMAO, I don’t know what’s going on.
> 
> *)*
> 
> Teaser for (hopefully) next chapter:
> 
> “Genos! Don’t slap the ball to hard, dammit! At this rate, you’re going to finish our entire stock of volleyball!” Hinata groaned to the tall cyborg in front of him.
> 
> “I’m sorry. I am trying to understand this volleyball game. My Sensei likes them. He likes reading manga about it. The main character of the said manga looks like you,” Genos replied without really looking at Hinata.
> 
> Hinata’s eyes sparkled, “Ehhh? Like me? Guwaaah! Really?”
> 
> On the outskirt of Z-City, Saitama looked back at Kageyama who ran with all his might but still too slow for Saitama. Panting and sweating, the high school student glared at the bald hero.
> 
> “You… what the hell are you? Your speed is inhuman,” gasped and panted Kageyama.
> 
> “Maybe I should just left you on the flat…” Saitama said, without really meaning it.
> 
> The ground suddenly shook and both of the males looked up to the sky, to a creature lurked between two hills on the distance.
> 
> “Meoooowwww!” roared the creature, who stomped the trees on his way.
> 
> Kageyama looked up to a large black cat, approximately bigger than the biggest plane he ever saw on the airport, who had narrow eyes and messy fur. The cat appeared to wear some sort of red—jacket? Cape?
> 
> And on top of its head was a smaller cat with long, blond-coloured fur who looked unfazed by the fact that he was sitting on top of monster who destroyed forest in front of him.
> 
> Kageyama’s jaw dropped, “Kuroo and… Kenma?”
> 
> Saitama crossed his arms in front of his chest, “You know them? Heee… interesting.”
> 
> *)*
> 
> I don't know whether I'll write the next chapter, LOL, I was just having fun.
> 
> Thank you for reading so far!
> 
> Edit on Monday, 14 December 2015: Since some people asked, I wrote more chapter. Head to the next one right away! 
> 
> Also, the teaser you just read doesn't necessarily reflect the exact next chapter, since by the time I wrote it I hadn't plan on what the second chapter would look like, but you WILL see Genos with volleyball at some point, considering he is now in Haikyuu!! universe. :D


	2. Chapter 2

**Notes for the Chapter:**

> Here's much longer chapter for the lovely people who commented on the first chapter. I love you to the moon and back!

"I know this may sound improbable, but you have to believe me for now, Ma'am."

Genos was sitting across Kageyama's mother. Hinata sat next to him, fidgeting and cowering. The woman who gave birth to Kageyama Tobio, however, smiled at the cyborg.

Hinata thought he had sat on that guest room for at least six hours, before he was greeted by cold, end-of-spring night wind outside Kageyama's house.

Since Genos and Kageyama had same voice and Genos ended up in a place where Kageyama supposed to be, Hinata and him concluded that Kageyama must be in his place instead. That mean Kageyama Tobio was now on Genos' city. It was called Z-city, if Hinata weren't mistaken.

Where was that city, anyway? It was a city where cyborg person like Genos existed. To Hinata, it sounded like a dangerous city. He hoped that Kageyama was fine. He hoped that, despite the fact that Genos was a perfectly civil cyborg, there was no evil and mean cyborg on Z-city.

Hinata had messaged the third years of volleyball club on Kageyama's disappearance and the theory on where he might be. After telling Kageyama's mother about his son's situation, Hinata felt like he had shared his worries to others and he didn't feel as worried as before.

Or so he thought.

But now, underneath dark, starry sky, with his bicycle rattling next to him, the left side of his shoulder—the place closest to Kageyama’s body when they walked home after long evening practice—felt cold.

Hinata looked at Genos, who was already staring at Hinata.

"You're worried about your partner Kageyama," stated the blond cyborg.

Hinata smiled weakly at Genos before looking down at his shoe, saying nothing in return.

"Please, be at ease. If Kageyama took my place, he would be with Master Saitama, which is the safest place on earth he could be."

"Master Saitama?" Hinata raised his face. The way Genos said ‘Master Saitama’ was like the way Nishinoya said Asahi’s name when Asahi wasn’t present. Or perhaps like the way everyone talked about the legendary Old Couch Ukai.

“Yes,” Genos nodded, glaring at Hinata.

Hinata was sure Genos didn’t mean to glare; it was just his main expression. Talking about glaring, Hinata knew another person who happened to be glaring and scowling all the time. The same person coincidentally had the same voice as Genos. Hinata wondered whether he sounded like Genos saying ‘Master Saitama’ when he talked about Kageyama.

“Is ‘Master Saitama’ your partner?” asked Hinata. He almost said ‘your precious, one-and-only partner’, but the words stuck on his throat. Was he really going to call Kageyama Tobio his precious, one-and-only partner? But it wasn’t thoroughly wrong, though, considering Kageyama could pass to Hinata perfectly on the court and no one had even come close to Kageyama’s skill in passing to Hinata.

Hinata might be just overthinking it, but he believed Genos’ expression turned slightly softer than before, “Master Saitama is my master. He is so much stronger and better than me. I don’t consider myself his partner.”

Genos’ voice turned quieter and quieter. His slightly glowing orange eyes also turned dimmer, so Hinata quickly responded, “But, Genos, this Master Saitama is, like, the closest person to you, right? It doesn’t matter if he were better and stronger than you!”

Genos raised his eyebrows at Hinata. Hinata wondered how old Genos actually was—or whether that mattered at all for a cyborg. Generally, people didn’t really think about machine’s age unless they got really old and need to be replaced. But Genos couldn’t be fully “machine”, right? Not with the way he talked about this ‘Master Saitama’, Hinata thought.

“According to general calculation, I am indeed the closest person to Master Saitama,” said Genos, though he sounded more like sighing. “But that doesn’t mean we’re equal or partners.”

Hinata tilted his head, “I think Kageyama is my partner.”

Genos blinked, “Is Kageyama stronger and better than you?” Then it came to Hinata that Genos didn’t know anything about Kageyama, except perhaps he knew Kageyama’s mother, location of his house, and the fact that they sounded eerily same. Since Hinata spent the majority of his waking time with Kageyama, he automatically thought that everyone must have known Kageyama as better as himself. Now Hinata realized that not every single person on earth knew Kageyama the way Hinata knew him and Hinata wasn’t sure what to do with such fact.

Hinata nodded, “Yes! Not only better and volleyball and also stronger in term of physical strength compared to me, Kageyama was also taller and smarter. Sure, we both flunked some subjects for the last mid-term, but, hey, I think we’re a set in playing volley. We are partners.” Hinata didn’t know why he felt so satisfied by saying the last sentence. He knew for sure Kageyama would say the same.

Kageyama Tobio would definitely say that Hinata Shouyou was his partner in volleyball.

Genos only stared at Hinata and said nothing for a while, “Huh. So it’s okay to call yourself partner to someone a thousand times better than you.”

Hinata chuckled, “I won’t say Kageyama is a thousand times better than me.”

Genos furrowed his eyebrows, “No?”

“No,” Hinata shook his head. “He’s approximately a million times better than me.”

*)*

“Hinata, Dear, is this ‘Genos’ a friend from your volleyball club of yours?” his mother whispered when they were both in the kitchen, presumably out of the reach of Genos’ ear.

Hinata threw a blank stare to his mother, “Does he look like high school student to you? Geez, Mum, he isn’t even human! I already told you, he got swapped with Kageyama from a town with monsters and heroes! Since he has nowhere to stay and I have to keep an eye to him in case he got swapped back with Kageyama, I asked him to stay with us. It’s okay, right? We have enough rice to feed him, right?”

Hinata’s mother raised one eyebrow, “He eats rice? Didn’t you just say that he’s a cyborg? It’s some sort of machine, right? That aside, we have enough food to feed seven Genos for weeks just fine, Hinata.”

Hinata sighed, “I better ask him about the food and everything, though. I hope he brings his own… charger or anything.”

When Hinata returned to the living room where Genos sat in formal sitting position, Natsu was staring at the blond cyborg.

“Nii-chan, what is this?” she asked, pointing her little index finger to Genos.

“Natsu! Please be polite! He is our guest, Genos!” Hinata ran to pull Natsu’s hand down as he glanced to Genos who only blinked at Natsu’s question.

“Our guest? Like Tobio-nii-chan? But he’s like Iron Man!” Natsu struggled to keep her finger towards Genos.

Hinata felt his cheeks gradually turned hotter. Sure, Natsu called Kageyama ‘Tobio-nii-chan’ all the time in front of Hinata and his mother, but calling him like that in front of people other than his family made Hinata wanted to stick his head to a nearby hole. Why must Natsu called Kageyama like he was Hinata’s officially married partner or something?

Genos finally opened his mouth, “What is this ‘Iron Man’? Does he iron clothes as his main job?”

Hinata laughed first, hard and uncontrollable. Natsu snorted, but then she looked pissed, “Don’t be rude to Mister Stark! He is an awesome hero! He can fly!”

Genos stared at Natsu. “I can fly too,” he said, the way Hinata’s mother saying, ‘I cooked miso soup for dinner’—like the most normal thing in the world.

Natsu blinked, “You CAN? Wait! You sound exactly like Tobio-nii-chan!”

Hinata, who had stopped laughing, remarked, “Wait, you just realized that, Natsu?”

Natsu pouted, “He looks nothing like Tobio-nii-chan! I mean, look at his hair and his scary arms!”

Hinata dragged Natsu out of the living room before his little sister makes another remark on Genos.

*)*

“Sorry for my sister,” Hinata sighed after he opened futon bed for Genos. “She’s in that time when she has to say everything on her mind, you know.”

Hinata looked at Genos, whose serious-expression reminded Hinata greatly to Kageyama. Genos shook his head a little, “I can understand. I think she’s nice.”

Hinata raised his eyebrows. Natsu just called Genos’ arms scary.

Genos looked at Hinata’s face and quickly added, “I don’t have sibling. I think I envy you a little because you have one and Natsu happens to be very cheerful and lively.”

Hinata laughed awkwardly, but also blushed, “Uh, I won’t call myself lucky! Oh wait, you didn’t say that. I mean, I should be the one envying you, Genos! You can fly! Ah, it’s already late. I have early training tomorrow, so I better sleep now.”

Genos nodded and they both slipped into their blankets before Hinata turned off the light.

Hinata almost dozed off to sleep, despite his worry about Kageyama, when Genos suddenly spoke, “Hinata.”

“Yeah? What is it?”

“Can Kageyama fly?”

“… No. People don’t really fly here. I don’t think human generally fly.”

“Well, I suppose not, unless you’re Tatsumaki. She’s S-Class Rank 2, by the way.”

Hinata had no idea who the hell was that or what were S-Class or Rank 2 was.

“Well, sorry to disturb your almost-sleep. I can sense your heartbeat was going slower when I called you. Now take a deep breath and try to sleep again.”

Hinata mumbled, “’Kay. Thanks, Genos.” He then sighed and closed his eyes.

If there were anyone ‘flying’ in the volleyball club, that person would him, Hinata Shouyou himself. But he could only fly when Kageyama was next to him. Clenching his fists, Hinata never wished so badly to have Kageyama toss to him again. He always took Kageyama’s toss for granted because he could get it daily.

Hinata would surely go to get toss from Kageyama again, right?

*)*

“Wow, Kagetobi, you were sure a big help back then.”

“Saitama-san, please don’t call me ‘Kagetobi’.”

“Ah, sorry, sorry. Kageyama it is.”

Kageyama walked next to the bald hero named Saitama, helping him carrying bags of groceries as they went home because it was already dark. Kageyama thought that no hero would go grocery shopping, especially not with extreme physical superpower like Saitama, but apparently he was wrong.

Saitama defeated Kenma and Kuroo faster than he normally would since Kageyama pointed out that Kuroo—(“The big black cat monster is Kuroo, Saitam-asan.”)—was merely the ‘body’ while Kenma was the brain. As long as Saitama snatched Kenma away and disconnected him from Kuroo, Kuroo wouldn’t be able to do anything. Kageyama didn’t know how that worked in this world, but it did, because the second Saitama grabbed Kenma, Kuroo roared and called for Kenma. Kenma apologized calmly on Saitama’s hand. They ended up going home, leaving Saitama and Kageyama alone, though Kuroo promised to bring his friends to defeat Saitama—and apparently Kageyama too—next time.

“So, Kageyama, in your world, Kuroo and Kenma are human, huh?” asked Saitama.

“Yes. They’re our rival in different high school. You see, the whole Kenma is the brain and the rest of the team including Kuroo is the body is actually their team strategy. In our first match…”

Kageyama talked about volley until reached Saitama’s apartment.

*)*

After dinner with curry—Saitama’s treat since Kageyama helped him with the cat monsters—Kageyama took a bath. He had to use Genos’ clothes and he was lucky to find one with sleeves, since most of them had no sleeves at all.

Saitama sat and read comic when Kageyama appeared in Genos’ presumably sleeping shirt and grinned. Kageyama had to choose the one with no sleeves, since he wasn't looking forward of wandering around outside tomorrow in a world he didn't know with sleeveless shirt. Despite being a setter, Kageyama wasn't exactly confident of his body that he'd display it to the world.

“Oh, it doesn’t really suit you, since you have no mechanical arms,” said Saitama plainly, like he was commenting weather.

“Genos had mechanical arms?” was Kageyama’s surprised response.

“Yes. I have his picture… here it is,” Saitama typed into Genos’ laptop and showed Kageyama a picture of male cyborg with short blond hair and orange glowing eyes.

“So I guess he’s in volleyball’s clubroom now…” Kageyama sighed. He could already imagine how Hinata would think that Genos was absolutely amazing-looking. Nishinoya and Tanaka would probably think the same. “Hinata would like his look.”

Saitama grinned through his plain expression to Kageyama, “Is ‘Hinata’ the orange-haired boy on your lock screen?”

Kageyama suddenly unable to swallow, “You saw my phone?”

“Sorry. The battery was dying and beeping, so I charged it,” Saitama gestured to the corner of the room, where Kageyama’s phone was charging next to the television.

Kageyama sighed, “That’s very considerate of you. And, yeah, Hinata is that boy on the lock screen.”

Saitama looked at Kageyama, “Is he your disciple in volleyball?”

Kageyama almost laughed at that, “No. We’re teammates. To be more exact, we’re like a set. Partners. I am setter and he can toss like crazy. It’s amazing.”

Saitama still had that grin on his face, “Ah. I see.”

“What’s with your grin, Saitama-san?” Kageyama pouted.

“Ah, no, it’s just that I’ve watched in television once that it’s a trend to have the photograph of your boyfriend or girlfriend on the lock screen of your phone. I actually thought Hinata was your boyfriend, Kageyama,” Saitama’s expression remained unchanged.

Across him, Kageyama wanted to explode.

“Wow, you’re really red. Was the bath too hot?”

Kageyama stood up, “I think I’m going to bed now.”

“Oh. You can use Genos’ bed and room.”

Kageyama nodded, entered his temporary bedroom, and slammed the door closed behind him.

He threw himself to bed and groaned, before forcing himself to sleep. For a while, he couldn't sleep and he couldn’t understand why. Then he remembered that his phone was on the living room and Kageyama missed his daily pre-bed routine of looking at Hinata on his phone before sleeping, building up excitement for playing with Hinata tomorrow morning.

After thrashing on the bed for sometime, Kageyama finally left the bed to get his phone on the living room. The battery was almost full when he returned and it was sometime after midnight. Kageyama stood on the dark living room, with the only source of light came from the screen of his phone, where Hinata smiled at him through pixels behind text that said ‘2:08 AM’.

Kageyama put his phone on his forehead, clasping it with both of his hands and sighed, long and low.

When he pulled back, he saw Saitama stood across the room in the dark. His bald head reflected the light from the outside a little. Kageyama must be staring at the older male so hard that he could see the edges of Saitama's lips twitching in suspicious way, like he wanted to smile but tried not to.

“Ah, sorry, Kageyama. I was thirsty, so I went to get water.”

Kageyama swore he could read Saitama’s thought, though the older male had returned to his bedroom and leaving Kageyama on that dark living room, clutching his phone in awkward manner.

The baldy hero must be thinking, ‘Oh, so Hinata _is_ Kageyama’s boyfriend or some sort. I guess the trend report on the television was correct, after all.’

**Notes for the Chapter:**

> \+ I need beta reader, I think. If you want to be one, do let me know, because my writing is a mess, LMAO.
> 
> \+ If you have any plots or ideas on this Kageyama/Genos swap story, do let me know as well!
> 
> \+ I've wrote the whole plot until the very end, so hopefully I can write everything down until "Demon Setter and King Cyborg" is finish. (Actually, just give me some comments and I'll probably write the whole thing faster.)
> 
> \+ Thank you so much for those commented, kudo-ed, bookmarked, subscribed and all. And, of course, thank you for reading this second chapter. Maybe we'll meet on the next one. :D


End file.
